Prosthetic heart valves, used to replace diseased natural heart valves, fall generally into two categories. The first category comprises heart valves with relatively rigid leaflets. These valves have 1, 2 or 3 leaflets formed of a stiff biocompatible substance, such as pyrolytic carbon. These valves, sometimes called "mechanical" valves, are often designed to have two leaflets pivoting in an rigid annulus, such as the design shown in U.S. Pat. No. 4,888,010 to Bokros.
The second category of prosthetic heart valves, called "bioprosthetic" valves, comprises valves with flexible leaflets, frequently made of a biological material. This second category can also be divided broadly into two classes. The first class comprises bioprosthetic heart valves typically including a wire stent frame with three flexible leaflets attached thereto. An example of such a valve is disclosed by Lane in U.S. Pat. No. 5,037,434, which is assigned to the assignee of my invention. These heart valves imitate the natural action of heart valves and so provide a structure which is relatively compatible with the cardiovascular system.
The second class of bioprosthetic heart valves do not have a stent or frame. They have the advantage of being constructed from flexible material, but they can be collapsed and deformed by the action of the heart.
Both classes of bioprosthetic heart valves are frequently constructed using biologic materials. Such materials are environmentally sensitive, and it is usual to protect the integrity of the valve from both impacts and contamination. Packaging for such valves has been provided wherein the valve floats or is retained within a bath of an appropriate fluid, such as ethanol. The packaging remains sealed until it is opened in the surgical theater, where implantation in a patient's heart is to take place. It is important, therefore, for packaging to provide an appropriate structure that can be easily manipulated both to protect the heart valve and to allow the valve to be implanted more easily and without risk of infection.